Compounds needles for warp knitting machines are known to include a needle stem having a hook at one end, and provided with a longitudinal groove in which is accommodated a slide carrying a closure cover member which in a closed position of the slide covers the end of the hook and which in an open position is concealed within in the groove behind a breast portion of the needle.
A compound needle of this type is disclosed in German patent Specification No. 1 760 140 (P 19 02). That compound needle involves the respective loop being carried by the needle stem until the slide has closed the opening of the hook. In order to ensure that that happens, the compound needle is of such a design that the transition between the closure member and the slide arm (which is referred to as the bend point) remains in the groove in the stem of the needle in every position in respect of the relative movement of the stem of the needle and the slide. That design gives rise to difficulties, particularly when there is a large number of yarns, for example six yarns, to be laid into the opening of the hook. In that case the hook opening must be of substantial length which in turn requires a correspondingly long closure member on the slide. That results in an undesirable reduction in the rigidity of the closure member and means also that, upon movement of the slide along the needle, the tip of the closure member can strike against the end of the hook, with consequential damage to the closure member or the hook.
In order to avoid that difficulty, it is already known from German laid-open aplication (DE-OS) No. 30 05 787 (P 29 84) for the closure member to be shorter than the opening of the hook, so that when the opening of the hook is closed by the tip of the closure member, the bend point on the slide, i.e. the junction between the closure member and the operating arm, has come out of the groove. In that case the slide is of such a cross-section that it carries the respective loop without being supported on the needle stem and/or by the hook end. That permits an increase in the size of the opening of the hook into which a correspondingly large number of yarns can be laid. In that arrangement, the slide is of such a configuration that the operating arm of the slide is still located in the groove in the stem of the needle when the slide is in the closed position. The slide is thus still positively guided even in the closed position. In that case, however, the slide which is correspondingly increased in length by virtue of the greater length of the opening hook requires a correspondingly increased amount of space for longitudinal movement in the rearward direction. That involves a correspondingly long needle stem, as, in the open position, the slide must be completely accommodated in the groove. The increase in length of the hook opening is subject to certain limits, by virtue of the above-mentioned necessary increase in length of the stem of the needle in a rearward direction.